Hydraulic fittings are used in systems for industrial equipment and commercial products to provide leakproof, full flow connections at various operating pressures. Elbow fittings of this type generally include two externally threaded ends, a body portion, an intermediate threaded portion, an O-ring, a washer and a lock nut. As an example of the use of such a fitting, one end of the fitting can mate with a female port and the other end can be attached to a rigid tube or flexible conduit. The hydraulics industry has relied on standards bodies, such as SAE, to regulate designs and dimensions so that the fitting can be interchangeable with other regulated mating parts.
SAE standards provide general and dimensional specifications for fittings. An example of such a fitting is shown in U.S. Pat. No. 3,240,515 to Schmohl. Manufacturers of the fittings provide end users with recommended assembly techniques for proper connections. However during installation of the fittings onto the mating parts, damage can occur to the fitting resulting in a leaking connection. In order to provide a leaktight connection, the O-ring must be properly sealed in a cavity formed by the washer, the female port, and the male fitting.
If an end user does not follow the recommended assembly technique the intermediate threaded portion on the male fitting can deform the washer. Damage to the washer disturbs the cavity and provides a leak path for the pressurized fluid. Damage to the washer can also result in damage to the O-ring. If the washer is deformed towards the O-ring, it can nick or cut the O-ring. Pressures inside the connection can also extrude the O-ring through any opening, e.g. the deformed washer, in the cavity.
Again if the end user does not follow the recommended assembly techniques the cavity can be too small to properly receive the O-ring. If the lock nut of the fitting is not in its correct position during installation, the washer will restrict the cavity. A restricted cavity will permanently deform the O-ring or contribute to the extrusion of the O-ring out of the cavity. Either occurrence can result in a leaking connection.
Fittings of this sort are intended to be used more than once. Reusable fittings can be connected to new conduits or a different female port. Damage to any component of the fitting will prevent the fitting from being reused. Specifically, damage to the washer can cause the same to bind on the body of the fitting. Damage to the O-ring can cause permanent deformation and the reduction in the usable life of the O-ring.